U.S. patent number 5,800,928 [Application Number 08/492,263] was granted by the patent office on 1998-09-01 for breathable waterproof film.
This patent grant is currently assigned to Elf Atochem S.A.. Invention is credited to Alain Bouilloux, Michel Degrand, Laurent Fischer, Yves Germain, Jean-Claude Jammet.
United States Patent |
5,800,928 |
Fischer , et al. |
September 1, 1998 |
Breathable waterproof film
Abstract
The invention relates to a breathing film constituting a mixture
including: (a) at least one thermoplastic elastomer which has
polyether blocks; (b) at least one copolymer including ethylene and
at least one alkyl (meth)acrylate. They can be used in combination
with fabrics or with nonwovens.
Inventors: |
Fischer; Laurent (Serquigny,
FR), Degrand; Michel (Bernay, FR),
Bouilloux; Alain (Bernay, FR), Jammet;
Jean-Claude (Glisolles, FR), Germain; Yves
(Serquigny, FR) |
Assignee: |
Elf Atochem S.A. (Puteaux,
FR)
|
Family
ID: |
9464394 |
Appl.
No.: |
08/492,263 |
Filed: |
June 19, 1995 |
Foreign Application Priority Data
|
|
|
|
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Jun 20, 1994 [FR] |
|
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94 07514 |
|
Current U.S.
Class: |
428/500;
428/523 |
Current CPC
Class: |
A61F
13/51458 (20130101); B32B 27/12 (20130101); A61F
13/5148 (20130101); C08L 71/02 (20130101); B32B
5/022 (20130101); A61F 13/51401 (20130101); C08L
77/12 (20130101); B32B 27/08 (20130101); C08L
23/08 (20130101); B32B 27/30 (20130101); C08J
5/18 (20130101); C08L 77/00 (20130101); D04H
13/00 (20130101); C08L 23/08 (20130101); C08L
2666/14 (20130101); C08L 23/08 (20130101); C08L
2666/24 (20130101); C08L 71/02 (20130101); C08L
2666/04 (20130101); C08L 77/00 (20130101); C08L
53/00 (20130101); C08L 77/00 (20130101); C08L
23/00 (20130101); C08L 77/12 (20130101); C08L
2666/24 (20130101); C08L 77/12 (20130101); C08L
23/00 (20130101); C08L 77/12 (20130101); C08L
2666/06 (20130101); Y10T 428/31938 (20150401); C08L
23/0869 (20130101); B32B 2307/7265 (20130101); A61F
2013/51431 (20130101); Y10T 442/678 (20150401); C08J
2377/12 (20130101); Y10T 442/674 (20150401); B32B
2307/724 (20130101); B32B 2305/18 (20130101); Y10T
428/31855 (20150401); B32B 2274/00 (20130101) |
Current International
Class: |
C08L
71/02 (20060101); A61F 13/15 (20060101); C08L
77/12 (20060101); C08L 71/00 (20060101); C08L
77/00 (20060101); B32B 27/08 (20060101); B32B
27/12 (20060101); D04H 13/00 (20060101); C08L
23/00 (20060101); C08J 5/18 (20060101); C08L
23/08 (20060101); B32B 027/00 () |
Field of
Search: |
;428/500,523 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0 378 015 A1 |
|
Jul 1990 |
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EP |
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0 459 862 A1 |
|
Dec 1991 |
|
EP |
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0 560 630 A1 |
|
Sep 1993 |
|
EP |
|
Primary Examiner: Pezzuto; Helen L.
Attorney, Agent or Firm: Pennie & Edmonds LLP
Claims
What is claimed is:
1. A breathable waterproof film of a mixture which comprises:
a) at least one thermoplastic elastomer having polyether blocks;
and
b) at least one copolymer of ethylene and at least one alkyl
(meth)acrylate.
2. The film according to claim 1, wherein said polyether blocks are
poly(ethylene glycol) blocks.
3. The film according to claim 1, wherein component b) is grafted
or copolymerized with (i) an unsaturated carboxylic acid, (ii) an
unsaturated carboxylic acid anhydride, or (iii) an unsaturated
epoxide.
4. The film according to claim 1, wherein component b) is a mixture
of (b1) and (b2) wherein
(b2) is a copolymer including ethylene and an alkyl (meth)acrylate,
and
(b1) is different from (b2) and is selected from the group
consisting of:
optionally grafted polyolefin homopolymers or copolymers;
optionally grafted copolymers of ethylene with at least one member
selected from the group consisting of (i) unsaturated carboxylic
acids, salts, or esters, (ii) vinyl esters of saturated carboxylic
acids, (iii) unsaturated dicarboxylic acids, salts, esters, or
anhydrides, and (iv) unsaturated epoxides; and
optionally grafted block copolymers selected from the group
consisting of styrene/butadiene/styrene, styrene/isoprene/styrene,
and styrene/ethylene/butene/styrene.
5. The film according to claim 4, wherein (b1) is a copolymer that
comprises ethylene, at least one alkyl (meth)acrylate, and an
unsaturated monomer having an acidic or carboxylic acid anhydride
functional group.
6. The film according to claim 1, wherein component a) is a
copolymer having polyamide blocks and polyether blocks.
7. A breathable waterproof film of a mixture which comprises:
a major proportion by weight of a thermoplastic elastomer
comprising a polyetheresteramide block copolymer; and
a minor proportion by weight of an ethylene/alkyl (meth)acrylate
copolymer and of an ethylene/alkyl (meth)acrylate/maleic anhydride
copolymer.
8. The breathable waterproof film according to claim 7, having a
thickness of from about 10 through about 80 micrometers.
9. The film according to claim 1 wherein the alkyl (meth)acrylate
is selected from the group consisting of n-butyl acrylate, isobutyl
acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, methyl
methacrylate, and ethyl methacrylate.
Description
FIELD OF THE INVENTION
The present invention relates to breathable waterproof films. The
breathable waterproof films of the present invention comprise at
least one thermoplastic elastomer that has polyether blocks and at
least one copolymer of ethylene and an alkyl (meth)acrylate.
BACKGROUND OF THE INVENTION
European Patent Application EP 378 015 describes breathable
waterproof films that are made of polyetheresteramides which may be
adhesively bonded by heating or with the aid of an adhesive onto
fabric, leather, or plastic.
European Patent Application EP 0 560 630 breathable waterproof
materials that consist (Example 6) of two coextruded films (1) and
(2). To each face of the film thus obtained, a nonwoven is
adhesively bonded with the aid of a polyurethane-based adhesive in
solution in trichloroethylene. The film (1) is a mixture of
polyetheresteramide, of polyamide 6, and of polyethylene grafted
with maleic anhydride. The film (2) consists of another
polyetheresteramide. A polyamide-based nonwoven is adhesively
bonded on the side of the film (1). A polyester nonwoven is
adhesively bonded on the side of the film (2).
Example 7 of the same prior art describes the same two-layer
material consisting of coextruded films (1) and (2), but a nonwoven
made of polyester/polyethylene is adhesively bonded on the side of
the film (1) and a nonwoven made of polyester is adhesively bonded
on the side of the film (2).
This material is employed for making garments by arranging the
polyester/polyethylene nonwoven on the inside of the garment and
the polyester nonwoven towards the outside of the garment. The
material makes the garment permeable to water vapour and impervious
to water and to blood splashed from the outside towards the
garment, thus protecting the person wearing the garment.
European Patent Application EP 459 862 describes films that consist
of a mixture of polyetheresteramide and of a modified polyolefin
chosen from: copolymers of ethylene and of vinyl acetate,
optionally maleinized; copolymers of ethylene and of (meth)acrylic
acid; copolymers of ethylene, of vinyl acetate, and optionally of
alkyl (meth)acrylate; and copolymers of ethylene, of alkyl
(meth)acrylate, and optionally of maleic anhydride.
These films may be adhesively bonded onto fabrics and
nonwovens.
Example 8-1 shows a film that consists of a mixture of a
polyetheresteramide and of a maleinized EVA adhesively bonded onto
a textile.
The thickness of the films described in EP 459 862 is from 100 to
500 .mu.m. They are not breathable waterproof films.
The breathable waterproof films of the prior art that are based
upon polyetheresteramides have the disadvantage, when they are very
permeable, of having a high moisture uptake which results in their
swelling and makes them fragile.
Films made of blend of polyetheresteramides and polyamides are not
supple enough and adhesively bond with difficulty to nonwovens.
SUMMARY OF THE INVENTION
Breathable waterproof films made of blends of polyetheresteramide
and copolyacrylates have now been found which have high
permeability while having low moisture uptake. A second advantage
of the films of the invention is that they are easy to extrude at
high speed and without faults. Moreover, they do not block and
their appearance is silky. A third advantage is that they have a
high elongation at break. A fourth advantage is that they can be
easily used in combination with nonwovens.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention is therefore a breathable waterproof film
that comprises a mixture including:
a) at least one thermoplastic elastomer which has polyether blocks;
and
b) at least one copolymer including ethylene and at least one alkyl
(meth)acrylate.
The thermoplastic elastomer may include polyether units and
polyester units; these are, for example, polyether blocks and
polyester blocks or units.
These products are known under the name of elastomer polyesters and
are thermoplastic.
The polyethers are, for example, polyethylene glycol, polypropylene
glycol or polytetramethylene glycol.
The molecular mass Mn of these polyethers may be between 250 and 6
000.
The flexible segments of the elastomer polyesters are formed by the
above polyether units and at least one dicarboxylic acid such as,
for example, terephthalic acid.
The rigid segments of the elastomer polyesters include glycol,
propanediol or 1,4-butanediol units and dicarboxylic acid units
connected by ester functional groups. The dicarboxylic acids may be
the same as those above.
The rigid segments may include a number of units resulting from the
action of a diol on a diacid.
The flexible segments may include a number of units resulting from
the action of the polyether on a diacid. The hard segments and the
flexible segments are attached by ester bonds. Such elastomer
polyesters are described in Patents EP 402 883 and EP 405 227.
The thermoplastic elastomers containing polyether units can also be
ester copolyetherimides. The flexible segments are formed by the
reaction of polyetherdiamines with tricarboxylic compounds or
carboxylic acid anhydrides containing a carboxylic group, such as,
for example, trimellitic anhydride. The polyetherdiamines employed
have an average molecular mass of 600 to 12 000. These
polyetherdiamines may themselves originate from polyethylene
glycol, polypropylene glycol or polytetramethylene glycol.
The polyester blocks forming the hard segments in the ester
copolyetherimides result, for example, from the condensation of at
least one diol with at least one dicarboxylic acid. The diol may be
glycol, propanediol or butanediol. The diacid may be terephthalic
acid. Such ester copolyetherimides are described in EP 402 883 and
EP 405 227.
The thermoplastic elastomers containing polyether blocks may also
be polyetherurethanes. They are formed by the chain sequencing of
three base components:
(i) a polyetherdiol such as, for example, a polyethylene glycol, a
polypropylene glycol or a polytetramethylene glycol. The molecular
mass may be from 500 to 6 000;
(ii) a diisocyanate such as an MDI or a TDI;
(iii) a diol of low mass such as glycol (ethanediol),
1,4-butanediol or 1,4-phenylene bis-.beta.-hydroxyethyl ether as
chain lengthener.
The elastomers (a) containing polyether blocks can also be polymers
containing polyamide blocks and polyether blocks.
Polymers containing polyamide blocks and polyether blocks result
from the copolycondensation of polyamide sequences containing
reactive ends with polyether sequences containing reactive ends,
such as, among others:
1) Polyamide sequences containing diamine chain ends with
polyoxyalkylene sequences containing dicarboxylic chain ends.
2) Polyamide sequences containing dicarboxylic chain ends with
polyoxyalkylene sequences containing diamine chain ends, obtained
by cyanoethylation and hydrogenation of aliphatic alpha,
omega-dihydroxylated polyoxyalkylene sequences called
polyetherdiols.
3) Polyamide sequences containing dicarboxylic chain ends with
polyether diols, the products obtained being, in this particular
case, polyetheresteramides.
The polyamide sequences containing dicarboxylic chain ends
originate, for example, from the condensation of
alpha,omega-aminocarboxylic acids of lactams or of dicarboxylic
acids and diamines in the presence of a dicarboxylic acid chain
limiter. The polyamide blocks are advantageously made of
polyamide-12.
The number molecular mass M.sub.n of the polyamide sequences is
between 300 and 15 000 and preferably between 600 and 5 000. The
mass M.sub.n of the polyether sequences is between 100 and 6 000
and preferably between 200 and 3 000.
The polymers containing polyamide blocks and polyether blocks may
also include randomly distributed units. These polymers may be
prepared by the simultaneous reaction of the polyether and of the
precursors of the polyamide blocks.
For example, it is possible to react polyetherdiol, a lactam (or an
alpha,omega-aminoacid) and a chain limiter diacid in the presence
of a little water. A polymer is obtained which has essentially
polyether blocks, polyamide blocks of very variable length, as well
as the different reactants that have reacted randomly, which are
distributed statistically along the polymer chain.
These polymers containing polyamide blocks and polyether blocks,
whether originating from the copolycondensation of polyamide and
polyether sequences prepared beforehand or from a one-stage
reaction, exhibit, for example, Shore D hardness values which may
be between 20 and 75 and advantageously between 30 and 70, and an
intrinsic viscosity between 0.8 and 2.5, measured in meta-cresol at
250.degree. C. with an initial concentration of 0.8 g/100 ml.
Whether the polyether blocks originate from polyethylene glycol,
polyoxypropylene glycol or polyoxytetramethylene glycol, they are
either employed as they are and copolycondensed with polyamide
blocks containing carboxylic ends, or they are aminated in order to
be converted into polyetherdiamines and condensed with polyamide
blocks containing carboxylic ends. They can also be mixed with
polyamide precursors and a chain limiter in order to make polymers
containing polyamide blocks and polyether blocks which have
statistically distributed units.
Polymers containing polyamide and polyether blocks are described in
U.S. Pat. Nos. 4,331,786, 4,115,475, 4,195,015, 4,839,441,
4,864,014, 4,230,838 and 4,332,920.
The polyether may be, for example, a polyethylene glycol (PEG), a
polypropylene glycol (PPG) or a polytetramethylene glycol (PTMG).
The latter is also called polytetrahydrofuran (PTHF).
Whether the polyether blocks are in the polymer chain containing
polyamide blocks and polyether blocks in the form of diols or of
diamines, they are simply called PEG blocks or PPG blocks or,
again, PTMG blocks.
It would not constitute a departure from the scope of the invention
if the polyether blocks contained different units, such as units
derived from ethylene glycol (--OC.sub.2 H.sub.4 --), from
propylene glycol ##STR1## or else from tetramethylene glycol
(--O--(CH.sub.2).sub.4 --).
The polymer containing polyamide blocks and polyether blocks
preferably includes only one type of polyamide block and only one
type of polyether blocks. Polymers containing PA-12 blocks and
polymers containing PA-6 blocks are advantageously employed.
It is also possible to employ a mixture of two or more polymers
containing polyamide blocks and polyether blocks.
The polymer containing polyamide blocks and polyether blocks is
advantageously such that the polyamide is the preponderant
constituent, that is to say that the quantity of polyamide which is
in the form of blocks and that which is optionally distributed
statistically in the chain represents 40% by weight or more of the
polymer containing polyamide blocks and polyether blocks. The
quantity of polyamide and the quantity of polyether are
advantageously in the (polyamide/polyether) ratio 1/1 to 3/1 and
preferably:
the elastomer (a) may be a mixture of two or more of the elastomers
containing polyether blocks referred to above, that is to say that
(a) may be a mixture of two polyetherurethanes or of a
polyetherurethane and of a polyetheresteramide or any other
combination.
The permeability to water vapour varies with the quantity of
polyether blocks of (a) and with the nature of these blocks. PEG is
very permeable to water vapour.
The alkyl group of the alkyl (meth)acrylate forming part of the
copolymer b may have up to 10 carbon atoms and may be linear,
branched or cyclic. By way of illustration of the alkyl
(meth)acrylate it is possible to mention especially n-butyl
acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, cyclohexyl
acrylate, methyl methacrylate and ethyl methacrylate. Among these
(meth)acrylates preference is given to ethyl acrylate, n-butyl
acrylate and methyl methacrylate.
According to a particular form of the invention the copolymer (b)
may be grafted or copolymerized with (i) an unsaturated carboxylic
acid such as, for example, (meth)acrylic acid, (ii) an unsaturated
carboxylic acid anhydride such as, for example, maleic anhydride,
or (iii) an unsaturated epoxide such as, for example, glycidyl
(meth)acrylate.
(b) may be a mixture of at least two of these copolymers.
According to another form of the invention, (b) is a mixture of a
polymer (b1) and of a polymer (b2).
(b2) is a copolymer including ethylene and an alkyl (meth)acrylate.
The alkyl (meth)acrylate may be that defined above.
(b1) is different from (b2) and is chosen from:
optionally grafted polyolefin homo- or copolymers such as, for
example, polyethylene, polypropylene and the copolymers of ethylene
with alpha-olefins, it being possible for these products to be
grafted with unsaturated carboxylic acid anhydrides such as maleic
anhydride or unsaturated epoxides such as glycidyl
methacrylate;
copolymers of ethylene with at least one product chosen from (i)
unsaturated carboxylic acids, their salts, their esters, (ii) vinyl
esters of saturated carboxylic acids, (iii) unsaturated
dicarboxylic acids, their salts, their esters, their monoesters,
their anhydrides, (iv) unsaturated epoxides;
it being possible for these ethylene copolymers to be grafted with
unsaturated dicarboxylic acid anhydrides or unsaturated
epoxides;
styrene/butadiene/styrene (SBS), styrene/isoprene/styrene (SIS) or
styrene/ethylene-butene/styrene (SEBS) block copolymers, it being
possible for these copolymers to be grafted with an unsaturated
carboxylic acid anhydride such as maleic anhydride.
The proportions of (a) and (b) are advantageously such that the
mixture is in the form of a matrix of (a) in which (b) is
dispersed, for example in the form of nodules. These proportions
depend on the nature of (a) and on the nature of (b) and in
particular on the acidic, anhydride or epoxy functional groups
which may be present in (b).
The quantity of a is advantageously more than 50 parts per 100
parts of (a) and (b), preferably from 55 to 80 parts. (These are
parts by weight, and so on in the remainder of the text).
A copolymer containing polyamide blocks connected to polyether
blocks is preferably employed as elastomer a, the connection being
made via ether bonds (polyetheresteramides).
It can be obtained by condensation of polyamide blocks containing
acid ends with polyether blocks containing OH ends.
Polyamides 6 and 12 and polyethylene glycols (PEG) are
preferred.
(b1) is advantageously a copolymer including ethylene, at least one
alkyl (meth)acrylate and an unsaturated monomer which has an acidic
or carboxylic acid anhydride functional group.
The unsaturated monomer of b1, which has an acidic or anhydride
functional group may be:
an unsaturated dicarboxylic acid anhydride such as citraconic
anhydride, itaconic anhydride, tetrahydrophthalic anhydride,
2-methylmaleic anhydride, 2,3-dimethylmaleic anhydride and maleic
anhydride;
an unsaturated acid or diacid such as (meth)acrylic acid, crotonic
acid or cinnamic acid.
The copolymer b1 is advantageously an ethylene-alkyl
(meth)acrylate-maleic anhydride copolymer containing, by weight, 2
to 10% of maleic anhydride and at least 50% of ethylene.
The alkyl (meth)acrylate of b1 may be chosen from the same class as
the (meth)acrylates of b2.
The copolymer b2 advantageously contains 5 to 40% by weight of
alkyl (meth)acrylate, and preferably 20 to 35%.
The thermoplastic film of the invention advantageously
includes:
a) a polymer containing polyamide blocks and PEG polyether blocks,
the polyamide being preferably PA-12;
b) a copolymer of ethylene and of an alkyl (meth)acrylate;
c) an ethylene/alkyl (meth)acrylate/maleic anhydride copolymer.
The preferred proportions are:
60 to 80 parts of a) 20 to 30 parts of b) and 5 to 40 parts of
c).
These films have a thickness which may be, for example, between 10
and 80 .mu.m and preferably from 15 to 35 .mu.m.
The polymer mixture which constitutes the breathing impervious film
of the invention may optionally contain organic and/or inorganic
fillers. Fillers which may be mentioned in particular by way of
example are silica and titanium oxide. The mixture may also contain
various additives, such as anti-UV agents, demoulding agents impact
improvers etc, as well as dyes or pigments.
These mixtures are manufactured by the usual techniques for mixing
as a melt, and are then converted into film by techniques which are
known per se.
The films of the invention are impervious to water and to aqueous
solutions and are permeable to water vapour and are not
microporous, that is to say that they are continuous films. They
have a good permeability to water vapour, which can reach 25 000
g/m.sup.2 /24 h according to ASTM standard E 96 BW (films in
contact with water).
They have a moisture uptake which is very markedly lower than that
of a film consisting essentially of a polymer including PEG
blocks.
They can be prepared by high-speed extrusion. The films do not
block, are flexible, have a silky feel and are not noisy.
These films can be used for making dressings, patches, ostomy
pouches and gloves.
The invention also relates to these objects.
The films of the invention can be bonded onto a textile or on to a
nonwoven essentially without adhesive, for example by laminating
with heating or by pressing. Adhesives may also be employed either
as a complete layer between the breathing waterproof film and the
nonwoven or as strips or any noncontinuous application such as
points or spots.
These adhesives may be hot melts.
The present invention also relates to these breathing waterproof
materials formed by the film of the invention used in combination
with a fabric or a nonwoven. It would not constitute a departure
from the scope of the invention to add other layers, either on the
side of the breathing waterproof film or on the side of the fabric
or nonwoven.
These other layers may be fabrics or nonwovens which are identical
with or different from those already present.
These breathing waterproof materials made of breathing waterproof
film used in combination with a fabric or a nonwoven are flexible
and, as the film has a low moisture uptake, it delaminates less
easily from the fabric or the nonwoven than does a film consisting
only of polymer containing polyether blocks. These materials are
useful for making protective garments for medical personnel,
disposable hygiene articles, mattress draw sheets, roof-lining
films for houses, clothing and footwear.
EXAMPLES
Product (A): namely a polyetheresteramide consisting of block
sequences of polyamide 12 M.sub.n =1 500 and of block sequences of
polyether glycol (PEG) (M.sub.n =1 500). The intrinsic viscosity,
measured at 20.degree. C. in meta-cresol is 1.45 to 1.60.
Product (B): namely a polyetheresteramide consisting of sequences
of polyamide 12 (M.sub.n =4 500) and of block sequences of
polyether glycol (PEG) (M.sub.n =1 500). The intrinsic viscosity,
measured at 20.degree. C. in meta-cresol is 1.4 to 1.55.
Product (C): namely a polyetheresteramide consisting of block
sequences of polyamide 6 (M.sub.n =1 500) and of block sequences of
polyether glycol (PEG) (M.sub.n =1 500).
Product (D): namely an ethylene-acrylic ester copolymer containing
24% by weight of methyl acrylate.
Product (E): namely an ethylene-acrylic ester copolymer containing
28% by weight of methyl acrylate.
Product (F): namely an ethylene-acrylic ester-maleic anhydride
terpolymer containing 19% by weight of comonomer and 3% by weight
of maleic anhydride.
The following mixtures are produced on a Buss PR 46/70 11 D and are
extruded under standard conditions suitable for 25-.mu.m film
products.
______________________________________ Product Product Product
Product Product Product (A) (B) (C) (D) (E) (F)
______________________________________ Mixture 1 60 30 10 Mixture 2
60 30 10 Mixture 3 20 70 10 Mixture 4 65 35
______________________________________
The water vapour permeability is measured according to the method
described in ASTM standard E 96 method BW (film in contact with
water) in a Heraous Votsch oven in conditions of
temperature=38.degree. C. and ambient relative humidity=50%,
maintained throughout the period of the measurement.
The water vapour permeability result is given in g/m.sup.2 /24
h.
The measurement errors yield a result of plus or minus 10 to
20%.
The moisture uptake of the products is measured using the weight
increase of granules which are soaked for 24 h in water at
20.degree. C. and conditioned beforehand in an atmosphere at
20.degree. C. and 65% relative moisture for 15 days.
The extrudability of the products is evaluated by measuring the
maximum drawing speed for producing a 25-.mu.m film without having
any phenomenon of resonance of the film edges ("necking") on
leaving the extruder.
The blocking of the film reeled after extrusion is evaluated
qualitatively using the ease of separation of 2 rolled-up
films.
The pleasant feel of the film is evaluated manually.
The noisiness of the film when crushed is evaluated; a "good"
result being the absence of noise.
The following table is obtained:
______________________________________ Permeability Products to
water Mositure Extrud- Film or vapour uptake ability block- Feel
Noise mixtures g/m.sup.2 /24 h (%) (in m/min) ing (*) (*) (*)
______________________________________ (A) .sup. 23 000 50
.ltoreq.50 - 0 0 (B) .sup. 12 000 12 .ltoreq.60 + 0 - (C)
.gtoreq.20 000 120 0 (D) or (E) .ltoreq.350 .ltoreq.2 .gtoreq.100 +
+ + 1 .sup. 22 000 27 .gtoreq.100 + + + 2 .sup. 11 000 8
.gtoreq.100 + + + 3 .sup. 300 5.5 + 4 .sup. 22 000 27 .gtoreq.100 0
0 + ______________________________________ (*) (+) Good (0) Average
(-) Bad
The tensile modulus is measured according to ASTM standard D 882
(strip w=15 mm, s=10 mm/min, 1.sub.o =100 min) on the films in
question in the direction perpendicular to and the direction
parallel to the extrusion.
______________________________________ Product (A) 1 (B) 2
______________________________________ Direction parallel to the
extrusion Modulus 79 MPa 46 MPa 235 MPa 189 MPa Breaking stress 30
MPa 29 MPa 50 MPa 61 MPa Break elongation .gtoreq.600% .gtoreq.600%
.gtoreq.500% .gtoreq.500% Direction perpendicular to the extrusion
Modulus 80 MPa 42 MPa 230 MPa 162 MPa Breaking stress 22 MPa 23 MPa
43 MPa 38 MPa Break elongation .gtoreq.600% .gtoreq.600%
.gtoreq.600% .gtoreq.600%
______________________________________
It is seen that:
Mixture 1
Retention of the permeability to water vapour, compared with
(A);
Decrease of nearly a half in moisture uptake, compared with
(A);
Increase in the extrudability speed, compared with (A);
Better feel, compared with (A);
Much less blocking, compared with (A);
Better adhesion to PP or PE nonwoven, compared with (A).
Retention of the mechanical properties at break (elongation,
stress), but very marked decrease in the modulus of the film. The
film is more supple, less noisy and the feel is silky.
Mixture 2
Same as Example 1, compared with (B).
Mixture 3
No improvement in permeability, compared with (E).
Mixture 4
Same as Example 1 with less improvement in the blocking and the
feel.
* * * * *